Field of the Invention
The invention relates to the field of surgical holding systems and in particular to a fastening device for surgical holding systems, to a surgical holding element and to a tool for surgical holding systems.
Description of Related Art
Surgical holding systems, for example for fixing broken bones, often consist of plates that are fastened into the bone by way of screws. The plates comprise openings, into which the screws are inserted at different angles. A surgical holding system is known from WO 2010/121388 A1, which is owned by the present applicant, with which a joint head of a screw with a joint socket in a plate forms a ball joint. The orientation of the screw in the joint socket is fixable by way of an eccentrically designed clamping ring. The clamping ring for this is rotatably mounted in the plate and on rotation clamps against the joint head of the screw.
Thereby, the problem of exactly two contact points between the joint head on the one hand and the joint socket and the clamping ring on the other hand results with the clamping, due to the geometry of the ball joint and the clamping ring. This is a consequence of the non-ideal shape of these parts due to manufacturing tolerances. Although it is then possible for the parts to plastically deform by way of continued, heavy tensing of the clamping ring, and for further contact points to arise, however, if this does not happen then the two contact points define an axis, about which the joint head can rotate with respect to the joint socket, so that the connection is not correctly locked (arrested) under all circumstances.